Sm doped borophosphate phosphors, SrBPO5, BaBPO5, Ba3BP3O12, and Sr6BP5O20, were prepared by solid-state reaction method. These samples were in good agreement with the reported powder patterns and a signal phase by the powder X-ray diffraction analysis. After the X-ray irradiation to the samples, it was found that part of Sm3+ ions changed to Sm2+ ions observed by photoluminescence (PL) spectra. The PL intensity of the valence changed Sm2+ ions increased with increasing X-ray irradiation time in short time range, and saturated for a long time irradiation. The saturated PL intensities were increased in the longer X-ray penetration depth in each sample. The results of the time dependence on PL intensities were agreed with our simulations which were assumed that the valence changes from Sm3+ ions to Sm2+ ions were the same probability in each Sm3+ ion. We found that Sm3+ ions doped in Ba3BP3O12 and Sr6BP5O20 had a better sensitivity on a valence change to Sm2+ ions by X-ray irradiation.